Ok this may be an obvious question to some folks but I was wondering if you could make sander style antennas for 2.4Ghz video tx and rx?
Reason being I have all the parts here to make some sander style antennas and I am in need of some video antennas!
If so what length would they need to be for 2.4Ghz.
Thanks
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A Sander style antenna for 2.4ghz vtx`s are the rubber duck antennas you get in the box with them. Standard monopole.
Have a look here for sizes and understanding of tuning my friend!
http://www.antenna-theory.com/antennas/halfwave.php (http://www.antenna-theory.com/antennas/halfwave.php)
Quote from: Coyote on May 05, 2014, 08:58:38 PM
A Sander style antenna for 2.4ghz vtx`s are the rubber duck antennas you get in the box with them. Standard monopole.
Thanks, I did think this. So I just need to replicate these.
Quote from: BenLimeClouds on May 05, 2014, 08:59:48 PM
Have a look here for sizes and understanding of tuning my friend!
http://www.antenna-theory.com/antennas/halfwave.php (http://www.antenna-theory.com/antennas/halfwave.php)
Thanks for the link, very useful. So I take it the standard "rubber duck" monopoles are 1/4 wavelength? So should follow this - http://www.antenna-theory.com/antennas/monopole.php (http://www.antenna-theory.com/antennas/monopole.php) ?
Quote from: Anarchy83 on May 05, 2014, 09:24:01 PM
Thanks for the link, very useful. So I take it the standard "rubber duck" monopoles are 1/4 wavelength? So should follow this - http://www.antenna-theory.com/antennas/monopole.php (http://www.antenna-theory.com/antennas/monopole.php) ?
No, they'll probably be a sleeved dipole. Regardless that's what you will want to build for a VTX / VRX. So two 1/4 wave elements to make up a dipole, one for the driven element, one for the ground plane. So follow the link BenLimeClouds gave you.
Neil.
To be honest with you there a bit pants for video!
You can make a skew or helical for you video that gets rid of multi path signals! Quite easy to make basic ones and you can use the stuff you have :)
The sander style ones are ideal for things like 459mhz or 433mhz not ideal for video!
Quote from: Anarchy83 on May 05, 2014, 09:24:01 PM
Quote from: BenLimeClouds on May 05, 2014, 08:59:48 PM
Have a look here for sizes and understanding of tuning my friend!
http://www.antenna-theory.com/antennas/halfwave.php (http://www.antenna-theory.com/antennas/halfwave.php)
Thanks for the link, very useful. So I take it the standard "rubber duck" monopoles are 1/4 wavelength? So should follow this - http://www.antenna-theory.com/antennas/monopole.php (http://www.antenna-theory.com/antennas/monopole.php) ?
Yes a rubber duck is an electrically short monopole antenna. The link is correct about making the antenna, if your making a monopole then your active element wants to be around 30 - 32mm depending on tuning point for 1/4 wavelength.
Dipoles work better ( but not as good as circular polarization ) in which case you make two elements each of 1/4 wavelength.
Quote from: Coyote on May 05, 2014, 09:55:53 PM
Quote from: Anarchy83 on May 05, 2014, 09:24:01 PM
Quote from: BenLimeClouds on May 05, 2014, 08:59:48 PM
Have a look here for sizes and understanding of tuning my friend!
http://www.antenna-theory.com/antennas/halfwave.php (http://www.antenna-theory.com/antennas/halfwave.php)
Thanks for the link, very useful. So I take it the standard "rubber duck" monopoles are 1/4 wavelength? So should follow this - http://www.antenna-theory.com/antennas/monopole.php (http://www.antenna-theory.com/antennas/monopole.php) ?
Yes a rubber duck is an electrically short monopole antenna. The link is correct about making the antenna, if your making a monopole then your active element wants to be around 30 - 32mm depending on tuning point for 1/4 wavelength.
Dipoles work better ( but not as good as circular polarization ) in which case you make two elements each of 1/4 wavelength.
Again thanks for this. I am not planning flying long distances. Planning on using it for an edf jet, so mainly flying around the runway so monopole should be more than what I need.
So if 2.4Ghz 1/4 wavelength is only around 30-32mm is it worth making them 1/2 wavelength i.e 60-64mm.
Would this improve anything?
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Quote from: Anarchy83 on May 05, 2014, 10:04:27 PM
So if 2.4Ghz 1/4 wavelength is only around 30-32mm is it worth making them 1/2 wavelength i.e 60-64mm.
Would this improve anything?
No, a 1/2 wave dipole made from 1/4 wave elements is optimal, see this video (https://www.youtube.com/watch?v=iInJkG8YPkA).
As previously said though circular polarised are better for short ranges as they cancel out reflections. Arguably linear antennas are better for longer ranges.
Neil.
Quote from: iPeel on May 05, 2014, 10:08:11 PM
Quote from: Anarchy83 on May 05, 2014, 10:04:27 PM
So if 2.4Ghz 1/4 wavelength is only around 30-32mm is it worth making them 1/2 wavelength i.e 60-64mm.
Would this improve anything?
No, a 1/2 wave dipole made from 1/4 wave elements is optimal, see this video (https://www.youtube.com/watch?v=iInJkG8YPkA).
As previously said though circular polarised are better for short ranges as they cancel out reflections. Arguably linear antennas are better for longer ranges.
Neil.
Wow learnt so much already. So if I made half wavelength mono, this will actually generate a full wavelength and therefore no radiation is produced. I will stick with 1/4 wavelength. May try a cloverleaf, see how I get in with these monopoles.
What is the actual formula for finding the correct size for antenna length?
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What is the actual formula for finding the correct size for antenna length?
[/quote]
Speed of light (in metres per second) divided by frequency (for a full wavelength), divide this by 4 to get a quarter wave.
So, we can use:
300/2400/4 = 0.03125 metre (or 31.25mm)
HTH
Nigel.
Quote from: Devonian on May 05, 2014, 11:03:36 PM
What is the actual formula for finding the correct size for antenna length?
Speed of light (in metres per second) divided by frequency (for a full wavelength), divide this by 4 to get a quarter wave.
So, we can use:
300/2400/4 = 0.03125 metre (or 31.25mm)
HTH
Nigel.
[/quote]
That's a great help. Thanks!
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Based on this formula, Why does Sander make the 433Mhz monopoles 164mm long? Surely they should be 173mm?
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Er, are we sure light only does 300m per second? I beg to differ :laugh:
Quote from: Anarchy83 on May 06, 2014, 12:00:34 AM
Based on this formula, Why does Sander make the 433Mhz monopoles 164mm long? Surely they should be 173mm?
Because you are using the speed of light in a vacuum, not the speed of light through copper. Multiply the result by a shortening factor of 0.95 for copper and you should get your result.
The dielectric effect of the material you surround the antenna with (e.g. RC aerial tubing) also plays a small part.
Neil.
Quote from: Steve W on May 06, 2014, 12:31:06 AM
Er, are we sure light only does 300m per second? I beg to differ :laugh:
you're quite right steve, but we use 300 and megahertz, gets rid of all those 0s.
devonian, frequency in megahertz.
Quote from: Steve W on May 06, 2014, 12:31:06 AM
Er, are we sure light only does 300m per second? I beg to differ :laugh:
38 mph apparently (17 m/s) ...
http://abcnews.go.com/Technology/story?id=99111 (http://abcnews.go.com/Technology/story?id=99111) :)
regards
Andy
some good information and links here, will take a proper read when I'm home.